This invention relates to a process and an arrangement for activating and arresting the operation of a heat-forming machine for manufacturing deep drawn plastic containers out of thermo-plastic foil material. This application relates to a copending application of the same inventor and is co-assigned with the instant application, filed on Sept. 28, 1978. and entitled ADVANCING ARRANGEMENT FOR ADJUSTABLE STEP-WISE ADVANCING DISTANCE. In this heat-forming machine there is paid out from a storage roller a foil band which is guided first to a heating arrangement and then to a molding and deforming arrangement and thereafter passes through a filling arrangement. A second storage roller pays out a cover strip which is welded on top of the deformed foil band in a welding arrangement. Finally the so-welded band is passed through a punching and ejecting arrangement. The heating arrangement includes upper and lower arranged heating elements which are mounted above and below the path through which the foil band material travels. The heating arrangement further includes screening plates which are slidably mounted between the heating elements and the foil band material. These plates serve to protect the foil band material against successive heating by the heating elements.
The invention furthermore includes the process for carrying out the activating and arresting of the heat-forming machine of the invention.
A heat-forming machine of the afore-described type is described in German published patent application No. 1 145 784 which corresponds to U.S. Pat. No. 3,000,157. In the heat-forming machines forming the state of the art, the foil cover material is pulled off from a storage roller and then pulled through the entire machine until it is gripped by a drive mechanism disposed at the end of the machine. In a similar manner the covering foil band material is pulled through the machine, thereafter the screening plates are pulled out of the heating arrangement and the machine is put into operation. In this known arrangement there exists the possibility to keep the filling arrangement inactive until a flow-free container is formed from the foil band material and has reached the operative region of the filling arrangement. In order to stop the operation of the machine, the screening plates are pushed into the heating arrangement and the machine can thereafter be stopped.
Obviously there results a great waste of foil band material in this type of procedure in view of the fact that the foil band material must be completely pulled through the machine before the machine is operational so that the region of the foil band material disposed between the heating arrangement and the drive mechanism for pulling the foil band is not usable. A similar drawback results at the time of arresting the heat-forming machine. This is evident from the fact that in the known heat-forming machines it is not possible to process completely the already formed containers which have not yet reached the punching and ejection mechanism.
A further drawback in the known heat-forming machines resides in that even just a temporary stopping of the machine produces a waste of the material that has already been formed but has not yet reached the stamping and ejection mechanism.
A further drawback of the known heat-forming machines resides in that even a temporary stopping of the machine causes the waste because thereafter a long segment of the thermo-plastic foil band material can no longer be used. This is evident from the fact that in the known machines the foil band material is subjected to a plurality of successive process steps before the foil band material has been completely processed.
Lastly, there results a considerable amount of waste of foil band material when a storage roller approaches its end and the end of the foil band material must be glued to the starting end of a new foil band material roll. In such a case the machine must be arrested before reaching the region in which the two ends of the foil band material are glued to each other and the glued together portion has reached the heating arrangement; thereafter the entire foil band material strip must be pulled through the machine up to the region in which the two ends have been glued together prior to the re-activating of the heat-forming machine. This is due to the fact that the glued region can obviously not be processed through the heat-forming machine, so that it is necessary to interrupt the heat-forming process in that region. Since, however, as has been described hereinabove, the temporary interruption of the forming process and the immediate subsequent actuation of the subsequent arrangements is not possible with the known heat-forming machines, it is only possible to operate these known heat-forming machines in the afore-described manner.